


Three to Tango

by FitofPaige



Category: Undertale (Video Game)
Genre: Alternate Universe, Ballroom Dancing, Belly Dancing, Cute, Dancetale, Dancing, Dating, F/F, F/M, Fluff, Fun, Gender-Neutral Frisk, Good W. D. Gaster, Grillster, Humor, Love, M/M, Multi, No More Resets (Undertale), Nonbinary Frisk, Pole Dancing, Polyamory, Reader Is Not Chara, Reader Is Not Frisk, Reader-Insert, Sex, Undertale Monsters on the Surface, im sure there will be angst, lighthearted mostly, playful rivalry, there will always be smut because apparently I can't stop writing smut, there will be smut
Language: English
Status: In-Progress
Published: 2018-03-03
Updated: 2018-03-13
Packaged: 2019-03-26 03:07:09
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 2,557
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/13848765
Author URL: https://archiveofourown.org/users/FitofPaige/pseuds/FitofPaige
Summary: Every monster has a dance that resonates in their soul, it’s what they use to solve disagreements, burn off steam, and make new friends. Ever since being freed from Mt. Ebott 10 years ago, they’ve spread happiness all through the world with their dancing.You are a new dancing instructor at a local dance studio, and on your very first day you manage to peak the interest of two very handsome monsters who begin fighting for your attention. Which one will win your heart?...Or will you even need to choose?NOTE: Please do not assume that this is a love triangle fic, because it really isn't ;)





	1. So the Games Begin

**Notes for the Chapter:**

> OH MY GOD WHAT HAVE I DONE, WHY AM I STARTING ANOTHER FIC?!
> 
> Oh well, here I am!
> 
> GET READY FOR SOME GRILLSTER/READER!!! PLEASE LEAVE A COMMENT BELOW!
> 
> (Also, this chapter is short, but I still think it ends perfectly ;) )
> 
> Enjoy!  
> -Paige

Grillby and Gaster stand in the dance studio, chatting after an intense training session. Today, Gaster had talked his fiery friend into joining him for Waltzing, which definitely isn’t his preferred dance style. Grillby humored him though, wanting to be supportive of his close friend.

“You did fairly well,” Gaster tells him, “but I can tell that it just doesn’t resonate with your soul.”

Grillby nods, “I had a good time, though.”

Gaster smiles and takes a swig from his water bottle. This isn’t anything new for the two monsters, the studio is like a second home to them in a way. They can usually be seen here practicing, or teaching others how to dance. Though it can be difficult to get away from work at times, with Grillby running his restaurant and Gaster working at the lab with Sans and Alphys, they always seem to find at least a little bit of time for one another.

“Maybe next week I can get you into the Salsa class.” Grillby says with a smirk.

Gaster huffs, “The only salsa I want any part of is the kind you make in your kitchen.”

Grillby chuckles, the flames on his head crackling, “You’ll come around.”

Gaster sighs with a small smile, “I guess since you tried Waltzing, I can at least try one of your dances.”

“Maybe Swing is more your style?” Grillby jokes.

“Oh no, much too fast for me.” Gaster says, “I don’t know how you keep up with it given how old you are.”

Grillby narrows his eyes at the now-giggling skeleton and gives him a light push, “Look who’s talking.”

“Grillby, Dr. Gaster.”

The two look over to see Toriel, former queen of monsters, walking over. She smiles at the both of them, “How are you two today?”

“Doing well, thank you for asking, Ms. Toriel.” Gaster says, giving a slight bow. Although Toriel doesn’t consider herself royalty any longer, old habits die hard.

Toriel just gives a small laugh, “That’s good to hear. Have the two of you met our new instructor yet?”

They shake their heads. They know a new dance instructor had been hired, but hadn’t heard which dances they would be teaching or even what their name is.

Toriel turns to look behind her, cups a hand around her mouth and calls out a name the guys have never heard before. Immediately, a young woman turns from a group of people and heads over. 

You have a smile on your face and a perk in your step as you walk toward them. The first thing Gaster and Grillby notice is the confident way you carry yourself, the second is the smooth, melodic tone of your voice when you greet them.

“Hey, Toriel! Did you need me?” You ask.

Toriel smiles and turns back to the guys, placing a large paw on your shoulder, “This is ______, our newest instructor! _______, this is Dr. W.D. Gaster, and Grillby.”

“Hi! It’s nice to meet you both!” 

Gaster extends his hand first and you take it, your grip firm as you shake, “It is a pleasure to meet you Miss ______.”

“Agreed.” Grillby says, shaking your hand next, “What will you be teaching?”

“Mostly contemporary dancing,” you say excitedly, “but I might do some belly dancing classes if there’s enough interest!”

“Oh I’m sure there will be many people interested in that!” Toriel says, now clasping her hands together with delight.

“Of course! I’m certain Grillby would be  _ very  _ interested in that, actually.” Gaster says, elbowing the fire monster.

Grillby glares at him, “And what about you? You can stand to learn more than just Waltzing.”

“Ah, while you may be right my friend,” Gaster gestures to his midsection, “as you know, I don’t have a ‘belly’ to do belly dancing with.”

You and Toriel laugh, but Grillby just shakes his head and lets out a sigh. 

“I’ll let the two of you know if it happens! I’d be happy to see you both there!” You tell them, your eyes sparkling.

“Perhaps we should go ahead and make a list for signups.” Toriel suggests.

Your smile only grows as you look at her, “That’d be wonderful!”

Toriel places an arm around your shoulder, “Then let’s go get it done! We’ll see you two later, boys.”

“It was nice meeting you!” You say, with a wave to them, “I’ll see you around!”

They return the goodbyes as you and Toriel walk off to the office. Gaster looks over at Grillby, smirking as he sees his gaze following you off.

“Don’t stare so hard, friend, you might burn a hole through her.” He chides.

Grillby rolls his eyes, “Like you weren’t ogling over her the entire time she was standing here.”

“Speak for yourself, Grillby!” Gaster gasps, “I do  _ not _ ogle.”

“Mm hmm.” 

“She does seem like a very nice person, though.” Gaster says.

“That she does.” Grillby replies, “Perhaps I will try out one of her classes sometime.”

“That eager to see more of her, are you?” 

Grillby furrows his brows, “I simply want to try out her form of dancing.”

Gaster laughs, “You just want to see more of her body.”

Grillby tries to fight it, but there’s the slightest of blue flames along his cheeks now, which makes Gaster laugh even harder. The fire elemental runs a hand down his face in frustration.

“Well, while you go learn how to make your stomach dance,” Gaster says once he’s calmed down, “I think I’ll just ask her out on a little date.”

Once again, Grillby’s eyes are mere slits of light behind his glasses as he turns back to his friend.

“Will you now?”

Gaster keeps his cheeky grin plastered on, “I believe I will.”

Grillby crosses his arms in front of his chest and turns to face Gaster fully, “Not if I ask her first.”

A look of surprise briefly passes over Gaster’s face before an eager grin takes its place, “Are you sure you’re up for the challenge?”

“Challenge? Are you insinuating that we make a game of this?” Grillby turns serious for a moment, “Because I don’t care to play around with someone’s feelings.”

“Oh, I don’t intend for this to be a game.” Gaster tells him, “I just don’t believe that she would choose you over me.”

“I would take offense to that if you weren’t so wrong.” Grillby quips. 

Gaster takes a step toward him, “You sound very confident in yourself, Grillby.”

“As well as you, Dings.”

Gaster raises a brow bone, “Shall we see who is able to win her heart?”

Grillby smiles, “As long as we don’t hurt her… Then sure, I accept your challenge.”

“Then let the games begin.”


	2. Put Your Best Foot Forward

**Notes for the Chapter:**

> Hey everyone! Sorry for the lack of updates lately, It's been a weird couple of weeks and I've just had no motivation to write. I AM still continuing this story AND Fireball, so don't you worry, chapters will be coming soon! :D
> 
> I'm really excited about the future of this story, and I hope y'all are too! Please don't forget to leave a comment, it brightens my day!
> 
> Enjoy!  
> -Paige

You’re smiling like mad when you leave your first contemporary class of the day, and the second one you’ve taught at the new studio. Despite the pace moving slow since the classes were for beginners, you’re left with an abundance of excitement flowing through your veins. You absolutely love all the students you’ve been teaching so far, and have no doubt in your mind that they’ll be able to move onto intermediate classes before they know it!

Walking to the locker room, you pass by the bulletin board where different flyers for classes and businesses are posted. You and Toriel made a sign up list for belly dancing classes yesterday and you glance over it to see if any new people have added their names. You recognize a few people from your contemporary dance class, and see some new ones you don’t know, but there’s one at the bottom that sounds familiar: Grillby.

Wasn’t that the fire monster Toriel introduced you to yesterday? He seems nice, and if you remember correctly, Toriel said he teaches Salsa here. If that’s the case, then he probably has a good handle on hip movements and will probably pick up on the dance style pretty quickly.

“Miss ______?”

The silvery voice pulls you from your thoughts and you look over to see the other monster you met yesterday, a tall, thin skeleton man with a crack coming from each of his eye sockets. He smiles sweetly at you, and you return it.

“Hi!.... It’s Dr. Gaster, right?” You ask.

He lets out a soft chuckle, “Just Gaster is fine, though I appreciate your politeness.” 

“Of course!” You say, “So, did you decide that you’d like to sign up for the belly dancing class after all?”

“Afraid not, I’m a bit too… old fashioned for that type of dance, if I’m being honest.” He says, giving an apologetic smile, “Though I wouldn’t mind sitting in a class just to see what it’s all about.”

Your grin widens at that. A lot of people are unsure about the style of dance, with all the hip gyrations and what not. It isn’t unusual for someone to sit in on a class and get a good look to see if it’s something they’d actually be interested in.

“You’re absolutely welcome to stop in anytime and watch!”

“I appreciate that.” He says, “I would like to extend that offer to you as well, if you are interested in the Waltz.”

“I’ve watched people waltz before, but I’ve never actually learned. I wouldn’t be opposed to giving it a try.”

His face lights up at that, “Why don’t you come to Friday’s class? It’s supposed to be a small group anyway.”

“I’ll have to take a look at my schedule, but I’ll keep that in mind.” You say, “Thanks!”

He simply nods and looks to the board, his eyes scanning the many flyers and sign-up sheets. After a few seconds, you hear him hum thoughtfully.

“Well, I should be going.” He says suddenly, turning on his heel, “I do hope I see you Friday.”

Before you can reply, he begins walking off. You watch him leave the studio in mild confusion. Just how busy is this man? Turning back to the board, you look at the list of different classes scheduled for the week. There’s quite a few that you’ve never tried before, even at other studios, that you now find yourself interested in.

You make a mental note to check some of them out later and start heading to the locker room again. As you enter, you can hear a loud voice talking very excitedly, as well a more quiet one, speaking rather calmly. Walking in further, you see two people talking. One, an extremely tall fish-like monster with blue scales, bright red hair tied up in a ponytail, and an eyepatch covering her left eye. The other is a human who you recognize as Frisk, the monster ambassador. Their long, brown hair is also pulled up, but is in place in a tight bun atop their head, their bangs nearly hanging in front of their eyes.

“Hey punk! Aren’t you the new contemporary dance instructor?!” The fish woman calls out as soon as she notices you.

You smile and step closer, reaching your hand out, “Yes! I’m _____. You must be Undyne, right? I believe Toriel told me about you yesterday. You teach hip-hop?”

Her sharp teeth are set in a wide grin as she quickly grabs your hand, gripping it tightly and shaking it so hard that your entire arm and upper body moves with it.

“Hip-hop and sometimes Capoeira! ” She says excitedly.

“Oooh, Capoeira! I may have to jump into one of your classes and try that out!” You tell her, trying not to wince as she squeezes your hand one last time before letting go.

“That’d be awesome! I was just telling Frisk here that me and my girlfriend, Alphys, are thinking of trying out your classes as well!”

You look to Frisk, who is now reaching their hand out, their brown eyes sparkle as they say, “It’s nice to meet you, _____. I’m Frisk.”

Their voice is as soft as their appearance as they stand there in a beautiful ballet outfit. You gladly take their hand, and the shake is much more gentle than Undyne’s.

“Good to meet you as well, Frisk!” You say with a smile, “Do you teach any classes?”

“Well, I’ve thought about it.” They tell you, “But I’m still taking lessons myself. Hopefully soon, though!”

“You’ll be done with school in no time, nerd!” Undyne says, giving them a light punch to the arm, “And then we’ll finally have another ballet instructor here!”

Frisk’s grin widens, “Thanks Undyne. I’ll do my best!”

“I know you will!” She replies before turning back to you, “I also saw the sign up list for your belly dancing class. Sounds pretty interesting!”

“I certainly think so!” You say, “It’s a lot of fun, but takes a good amount of core strength.”

“Ha! I don’t think it would be much of a challenge for me then!” Undyne says, slapping a hand against her bare stomach. Seeing how toned she is, you’re inclined to agree with her.

“Maybe you and Alphys should sign up for it as well.” Frisk suggests.

Undyne snickers, “It’s difficult enough getting her to agree to contemporary. I don’t know if she’d be comfortable enough with belly dancing.”

“I could always do a smaller class, or just work with the both of you.” You say, “Since you’re a trainer here, I wouldn’t mind setting aside some time for that.”

Undyne laughs loudly and brings a hand down on your shoulder. For a moment, you feel like your feet are going to sink through the floor, but she just holds you steady, gripping you enough to probably bruise.

“Hell, _____, that’s really nice of you!” She says, “Tell you what, let me talk to Alph about it, and we’ll see!”

“Sounds good!” You say, trying not to let out a relieved sigh as she pulls her hand away.

“I don’t know if I’d be very good at it.” Frisk chimes in, “I don’t feel like it’s really my style, but I did take a look at the sign up sheet, and it looks like you might need to put an extra one up there before long!”

You can’t help but beam proudly, “It’s so exciting! I didn’t expect for there to be so many people interested right away!”

“I even saw Grillby put his name up there!” Undyne huffs.

Frisk looks to her with a smirk, “Jealous, Undyne?”

“Maybe!” She yells, “I’ve been trying to get him into a capoeira class for ages! But he says it’s just too much like actual fighting for his tastes.”

“Well, he was a soldier.” Frisks says, “So he probably doesn’t want to be reminded of… that time.”

You look between the both of them, eyes wide in confusion, “Wait, Grillby was a  _ soldier _ ?! How… how does one go from that to teaching Salsa??”

Frisk and Undyne look at one another and shrug.

“I think the dancing routine calms him down, much like bartending does.” Frisk tells you.

You blink a few times, “He bartends too?”

Undyne throws her head back with a laugh before slapping your arm a little more gently than expected, “Looks like we’ve got a lot to show you _____! Whatta ya say, Frisk?”

“I say we take her over to Grillby’s right now!” They look to you with an even bigger smile than before, “So, you free for lunch?”

**Author's Note:**

> [CHAT ME UP ON TUMBLR!](https://fitofpaige17.tumblr.com/)  
>  Three to Tango Playlist: [HERE!](http://archiveofourown.org/works/12651807)
> 
> If you have an Undertale related drabble you'd like me to write, leave your request [HERE!](https://open.spotify.com/user/1249626311/playlist/2fJBNSb78a2yvv3V1DnokQ)
> 
> Also check out my other Undertale fics!  
> Sans/Reader: Safe Place, Spitfire, This Heart is a Stone  
> Grillby/Reader: Up in Flames, Fireball


End file.
